Recently, an environmental problem known as global warming which is caused by the excessive use of fossil fuels has become a serious problem. In addition, people's awareness to the problem of the exhaustion of fossil fuels has increased. To overcome these problems, the development of hydrogen energy which is one kind of alternative energy and the development of a sensor of contamination gas caused by environmental pollution have rapidly progressed. Currently, many technologies for using hydrogen energy have been proposed. However, hydrogen energy is highly explosive, unlike existing energies. Thus, a safety device should be employed when the hydrogen energy is used. To widely use hydrogen energy, a hydrogen detecting technology is required.